Combustion apparatus



May 2l, 1968 E, R, STEWART ET AL 3,384,442

COMBUSTION APPARATUS Filed Oct. 20, 1966 United States Patent Office 3,384,442 Patented May 21, 1958 3,384,442 COMBUSTION APPARATUS Elmer R. Stewart and Francis J. Verlramp, Indianapolis, Ind., assignors to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed Oct. 20, 1966, Ser. No. 588,020 1 Claim. (Cl. 431-264) ABSTRACT OF THE DISCLOSURE A miniature combustion .apparatus for a radiant energy conversion burner particularly characterized by .a fuel injector-igniter having an outer tube through which fuel is delivered into the combustion chamber so as to swirl around the walls and a miniature igniter mounted concentrically within the fuel tube.

Our invention is directed to improvements in combustion apparatus. More specifically, our invention relates to a combined fuel nozzle and flame igniter which is of such structure as to be feasibly constructed in very small sizes and, in view of the combination of the fuel injector and igniter in one miniaturized unit, to minimize the space required for fuel injection and ignition apparatus in a burner.

Our invention arose from the problem of improving performance of a small combustion chamber for a radiant energy conversion burner, the interi-or diameter of which is about one inch, and the invention is described herein in terms of this installation, but it is to be understood that our invention is suited to other applications.

The principal objects of our invention are to simplify and improve miniature burners; to provide a miniaturized fuel injector-igniter device; to provide such a device which provides favorable distribution of fuel in the air in a combustion chamber; to provide an igniter which is cooled by fuel and which needs no ground, and to provide .a simple, rugged, .and inexpensive fuel injector-igniter adapted for easy installation in combustion apparatus.

The nature of our invention and the advantages thereof will be apparent to those skilled in the art from the succeeding detailed description of the preferred embodiment of the invention and the accompanying drawings thereof.

FIGURE l is a vertical sectional view of a radiant energy conversion burner taken on a plane containing the axis of the burner.

FIGURE 2 is a fragmentary horizontal section taken on the plane indicated by line 22 in FIGURE l.

As a prelude to the description of our injector-igniter, it seems best first to describe the radiant energy conversion burner structure with which it is used. It may be noted that this burner is of a generally known type, and that our invention lies in the injector-igniter .and the combination of such an igni-ter with a burner. The burner comprises a cup-shaped base S defining a circumferential shoulder on which is mounted a ring 6. A cup-shaped combustion chamber part 7 includes a flange 9 which is seated on the top ofthe base 5 and spaces the combustion chamber part 7 from the base 5. The remainder of the com-bustion chamber 17 is defined by an inverted cup or closed cylinder 10 which rests upon and is centered by the flange 9. A heat-radiating outer Wall is defined by a cylinder 11 which rests upon the ring `6` and is centered by this ring so as to be spaced from the cylinder 10. A circular cover 13 rests upon and closes the top of cylinder 11. Air for combustion i-s introduced through a pipe 14 into the base 5 and flows into the combustion chamber through a number of apertures 15. Fuel Valso is introduced into the part 7 and combustion 'takes place within the combustion chamber 17 defined within the combustion chamber parts 7 and 10. The hot combustion products flow from the cylinder 10 through numerous small apertures 18 and flow within the outer shell 11 to a ring of exhaust ports 19 defined by slots in the lower margin of the cylinder 11. The shell 11 is heated to incandescence. The parts 5, 6, 7, 10, and 11 are made of some high temperature resisting ceramic material or silicon carbide. The cover 13 may be of similar material or may be a heat resisting metal. Temperature resisting metals such as Inconel or stainless steel may be used for the entire structure, but are not preferred.

The injector-igniter 21 of our invention comprises an outer tube 22 which is a fuel tube -and conducts fuel into the combustion chamber. This tube extends preferably along a radius of the burner and enters the combustion chamber near the bottom. A fuel conducting tube 23 enters the side of tube 22 and is supplied with suitable fuel under appropriate pressure from any suitable source and means for controlling the flow (not illustrated). In the preferred embodiment of the invention, the fuel used is propane gas, but the structure is not limited to any particular type of fuel.

The igniter part of our invention comprises a shell 25 including a tubular portion 26 extending through the fuel tube 22 and projecting from each end thereof and a connector 27 of any suitable type adapted to connect two ignition leads to the igniter. The shell 26 is preferably concentric with the tube 22 and the -two are structurally connected and sealed by annular welds 29'and 30 at the ends of the fuel tube.

The ignition electrodes are defined by two wires 31 extending through .the interior of the tubular shell 26 in generally parallel rel-ation and terminating at the combustion chamber end of -shell 26. These Wires are insulated from each other and from the shell by ceramic insulating material 33 packed within the shell. This structure is an adaptation of known .types of thermocouple structures and presents no technological problem. When high tension electricity is supplied to the igniter, a spark jumps between the ends of the electrodes 31.

The gaseous fuel is discharged from tube 22 within the combustion chamber 7 through `a lateral orifice 35 which causes the gas 35 to swirl within the chamber and mix rapidly and thoroughly with the combustion air. Since the fuel is a gas, the orifice 35 is of considerable size but, by using a suflicien-tly small 'hole and sufliciently high pressure, a liquid fuel may be atomized with essentially the same structure. So far as we are aware, this tangential fuel injection is new, so far as this sort of burner is concerned.

The fuel tube 22 extends through a hole 37 in the par-t 7 and through a hole 38 in the base 5. It is secured and sealed in the base by cement 39. The combustion air is supplied through pipe 14 which is mounted in an opening 41 in the bottom of the base 5 by cement 42.

In the operation of the burner, the air which is supplied is at high temperature, air preheated as high as l800 F. having been used. The injector-igniter is thus in a very hot environment and one of the -advantages of our invention lies in the fact that the fuel flowing through the tube 22 flows over the igniter shell and cools the igniter. The fuel is ordinarily supplied at room temperature. Thus, the fuel cools both the fuel injection tube and the en-tire igniter.

The structure illustrated is particularly suited 4to miniaturization and, in the preferred embodiment of the inven-tion, the fuel tube 22 is one-quarter inch outside diameter stainless steel tubing and the tubular portion 26 of .the igniter shell is one-eighth inch outside diameter stainless steel. The drawing, therefore, represents the device considerably enlarged. With this device installed as illustrated, a cylinder of only one-quarter inch diameter and approximately one-quarter inch long projects into the combustion space; thus, very little combustion space is occupied and the injector is suited to use in very small burners. Moreover, the small area of the injector exposed in the combustion chamber minimizes heat transfer -to it. Combining the injector and igniter results in a requirement for only one mounting hole for the device rather than two for separate devices.

The description of the preferred embodiment of the invention for the purpose of explaining the principles thereof is not to ybe considered as limiting or restricting the invention, since many modifications may be made by the exercise of skill in t-he art.

We claim:

1. A continuous combustion device comprising, in combination,

structure defining a combustion chamber of generally circular cross section having an annular side Wall, the side Wall having openings distributed over the wall for entry of an oxidizing gas,

a fuel tube extending through the side wall into the combustion chamber,

the fuel tube having a fuel outlet disposed to discharge gaseous fuel circumferentially of the combustion chamber so as to sweep past the said openings,

an igniter including an elongated shell extending through the fuel tube and projecting from the tube at each end,

igniter electrodes at the combustion chamber end of the igniter,

an electrical connector at the other end of the igniter,

`and

means for conducting gaseous fuel continuously to the fuel tube for flow Within the tube to the said outlet over the exterior of the igniter shell,

the fuel flowing through the tube being effective to cool the igniter.

References Cited UNITED STATES PATENTS 2,013,979 9/1935 Bray. 2,569,887 10/1951 Goddard. 2,892,733 6/1959 Gardner et al.

JAMES W. WESTHAVER, Primary Examiner. 

